Komatsu to Begin Sales of Thermoelectric Generation Modules

28 January 2009

Construction-equipment manufacturer Komatsu Ltd. will launch the commercial production and sales of thermoelectric generation (TEG) modules beginning in May.

Komatsu’s TEG modules, which are based on a bismuth (Bi) and tellurium (Te) material, have a conversion efficiency of 7.2% under a temperature differential of 280 °C on the high-temperature side and 30 °C on the low-temperature side. Under these conditions, maximum output is 24W per module, with a power density of approximately 1 W cm-2.

Komatsu says that its thermoelectric generation modules offer 50% or higher output power density compared to similar products on the market. Komatsu is conducting research in applications designed to regenerate electric energy from the exhaust gas from its diesel-powered construction equipment.

Komatsu is a wholly-owned subsidiary of KELK, a leading manufacturer of temperature-control equipment for use in semiconductor manufacturing and an integrated researcher, developer and manufacturer of thermoelectric modules, heat exchangers and applied products. KELK says it has the global leadership position for thermoelectric modules (Peltier devices).

Some areas of research in thermoelectricity are undertaken by Komatsu’s Research Division for the Komatsu Group. With respect to the thermoelectric generation module, Komatsu participated in the “Development for Advanced Thermoelectric Conversion Systems” (FY2002 - FY2006), an energy conservation program, sponsored by Japan’s NEDO (The New Energy and Industrial Technology Development Organization), and has commercialized the results of this program.

The thermoelectric generation modules will be exhibited in NEDO’s booth at the nano tech 2009 conference and expo at Tokyo Bigsight, 18-20 February. The announced price per module (minimum order of 50) is ¥30,000 (US$334).

I like the idea, it's still a bit pricy to be worthwhile. For a diesel with 220 g/kw-hr efficiency (typical) and $3/gal fuel, that works out to be 0.174 $/kw-hr. This TE is 13917 $/kw ($334/(24/1000 kw)). So the breakeven is about 80,000 hrs (13917 / 0.174). Or 4.8 million miles. They need to figure out how to bring the price down at least 10X or 100X.

Otherwise it would be great way to improve efficiency with little extra weight.

The real use of this item is to replace the alternator (generator) in a car or truck. This has been tried in the past and it did work, it was just not going to pay back.

Today with the high price of gas and this improved tech it gets 1/3 of the way there. You would use 20 moduals on the exhaust to create 500w. You could remove the alternator completely and have less drag on the engine. This is worth 5% or more in fuel savings. It needs to cost less then $500 to make it into regular auto use.

I know this site you normally talk about car issues but couldn't this technology also be used in your home, for example a woodburning stove might generate enough power using these modules to charge batteries and through an inverter to supply some of the power used in a home.

Tellurium is extremely rare, one of the nine rarest metallic elements on Earth.

With an abundance in the Earth's crust even lower than platinum, tellurium is, apart from the precious metals, the rarest stable solid element in the Earth's crust. Its abundance in the Earth's crust is 1 to 5 ppb, compared with 5 to 37 ppb for platinum.

Bismuth Telluride is a narrow gap layered semiconductor with a trigonal unit cell and point group symmetry of R3barm. The valence and conduction band structure can be described as a many ellipsoidal model with 6 constant energy ellipsoids that are centered on the reflection planes.[2] Bi2Te3 cleaves easily along the trigonal axis due to Van der Waals bonding between neighboring tellurium atoms. Due to this, Bismuth Telluride based material that is used for power generation or cooling applications must be polycrystalline. Furthermore, The Seebeck Coefficient of bulk Bi2Te3 becomes compensated around room temperature, forcing the materials used in power generation devices to be an alloy of Bismuth, Antimony, Tellurium, and Selenium.[3]..

Peltier effect describes the temperature difference generated by EMF and is the reverse of Seebeck effect. Finally, the Thomson effect relates the reversible thermal gradient and EMF in a homogeneous conductor.

Why should you be so concerned about your Peltier getting enough power? Because a non-functioning Peltier could actually be worse for your CPU than having no cooling at all! A non-functioning Peltier could actually be insulating your processor, because the Peltier element is not a good conductor of heat in and of itself. Most Peltier devices use bismuth telluride because it is both an excellent conductor of electricity and a poor conductor of heat. That kind of insulation is very bad, even for a non-overclocked CPU. Because the inside is air-tight, a non-functioning unit will produce conditions analogous to the inside of your mamma's El Camino with vinyl seats parked at the K-Mart in Phoenix on July 1st.

*: Units are mV/°C; all data provided at a temperature of 0 °C (32 °F)

The thermoelectric generator has found its best-known application as the power source in some spacecraft. A radioactive material, such as plutonium, generates heat and cooling is provided by heat radiation into space. Such an atomic power source can reliably provide many tens of watts of power for years. The fact that atomic generators are highly radioactive prevents their wider application.

Makes you wonder about selenium?

Selenium is found in a few rare minerals such as crooksite and clausthalite. In years past it has been obtained from flue dusts remaining from processing copper sulfide ores, but the anode metal from electrolytic copper refineries now provide the source of most of the world's selenium. Selenium is recovered by roasting the mud with soda or sulfuric acid, or by smelting them with soda and niter. Selenium is priced at about $300/lb. It is also available in high-purity form at a somewhat higher cost.

This seems like a very expensive way of recovering exhaust energy at $14/watt. Much more cost effective would be either mechanical or electric-turbocompounding (m-TC and e-TC). You can generate 20 to 60kW with an e-TC (depending on design & engine) and the cost is much lower, around $0.10 to $0.50/watt. Of course, TC systems have to be OEM fit, they are rarely optimized as after-market fits and they are currently only for heavy duty diesel engines.

Komatsu has announced that they start sales from May 2009.
But, even in December 2009, they do not respond to our inquiry. We want to check the efficiency of TEG that KOMATSU is claiming. for which we need 2 or 3 modules. In future we may purchase in 100 s if the TE modules are of 7.2% efficient. However, the cost per module should come down to at least US$ 50 in future.

Have you started manufacturing?
What is the initial cost per module?
Whether I can purchase 2 to 3 modules now?
"Heat can be reversed in your module to reverse the direction of current" is it correct?
"400 C is the maximum temperature that can be applied to your module on either side" is it correct?
Please answer to these questions.

Have you started manufacturing?
What is the initial cost per module?
Whether I can purchase 2 to 3 modules now?
"Heat can be reversed in your module to reverse the direction of current" is it correct?
"400 C is the maximum temperature that can be applied to your module on either side" is it correct?
Please answer to these questions.